This invention relates to self wound, water dissolvable, adhesive tape. More specifically, the tapes are dissolvable tapes, labels, and other adhesive markers with applications including, but not limited to, date marking labels, masking tapes, adhesive markers. The tapes are used in manufacturing, and other applications requiring an easily removable, pressure sensitive adhesive label or tape.
Food date marking labels are of vital importance to ensuring freshness in the food services industry. Properly and clearly marking food containers to ensure that freshness dates are not exceeded is essential to prevention of food poisoning and other contamination borne health problems. After use, however, these labels must be removed from reusable containers before subsequent refilling of said containers to guarantee cleanliness and removed from reusable containers before subsequent refilling of the containers to guarantee cleanliness and avoid contamination by bacterial or other matter. Removal of conventional labels or tape is difficult and imperfect because residual adhesive and label or tape substrate material tends to be left behind. For this reason, water xe2x80x9cdissolvablexe2x80x9d labels have come into widespread use in the food services and other industries.
In the food marking industry, the term xe2x80x9cwater dissolvablexe2x80x9d means that marking labels are readily and fully removed with agitated water, even though said labels may not be completely soluble in the chemical sense of that term, which would involve complete separation into chemical species (atoms or molecules). In this process, labels separate into cellulose fibers, adhesives, and other materials that comprise them, into a fine enough form that they may be carried away by the water. Dissolution is achieved because each component of the labels contain a sufficient quantity, and an appropriate distribution of water dissolvable material such that the entire body of the label substrate, any coatings or indicia on the label, and the pressure sensitive adhesive layer, are all readily washed away and cleanly removed by immersion in water with agitation. Similarly, water dissolvable adhesive tapes are available that can be used for marking or to adhere other materials.
These tapes, however, currently require the use of costly backing material which is typically coated with a silicone or other abherent (resistant to adhesion) material to allow for easy release of the pressure sensitive adhesive. The labels or tape are interleaved with this backing material on a roll for transportation, storage, and sale. Without this backing material, the pressure sensitive adhesive would bind to the top layer of the label or tape and impede or destroy the ability to unwind and utilize the label or tape. This would result because of the combination of time and temperature, along with pressure between each layer of adhesive tape. The time, temperature and pressure would result in admixture and adhesion of said adhesive to the top surface of said previous layer. The resulting requirement for an expensive abherent coated interleaving material, which is wastefully discarded subsequent to the removal of the labels or tape, adds a significant cost to water dissolvable marking labels and tapes and impedes their application.
Although a dissolvable tape is disclosed in U.S. Pat. No. 4,971,926, the tape described therein requires a fluorocarbon solvent. This presents serious environmental difficulties, in contrast with the water dissolution of the present invention. In addition, the patent describes a tape in which a protective layer of polyethylene terephthalate (P.E.T.) is utilized. The tape is silicone coated as an interleaving area, adding considerable expense. This high cost and the environmental issues severely limit the use of the prior art tape in areas outside electronic circuit board manufacture.
Still other tapes require an expensive and distinct abherent coated backing material, which is wastefully discarded subsequent to removal of the labels or tape, adds a significant cost to water dissolvable and tapes and impedes their application. It can be seen that the transfer of even a small amount of pressure sensitive adhesive from the bottom surface of a tape to the top surface of the subsequent layer would leave the tape with an unacceptable appearance and unsanitary, gummy top surface.
The present invention addresses the need for a low cost, water dissolvable adhesive tape by enabling such tape to be xe2x80x9cself-wound,xe2x80x9d that is, to be directly wound onto itself on a spool without the inclusion of an intervening layer of release material between each layer of labels or tape.
This invention is a family of adhesive tape structures and formulations that are comprised entirely of materials that are dissolvable by water, and which can be xe2x80x9cself woundxe2x80x9d that is, wound directly onto the previous layer of tape on a roll. This is achieved through the use of combinations of adhesive layer formulations and release layer formulations that are mutually abherent, that is, not susceptible to the formation of adhesive bonding, thereby allowing the easy unwinding of the tape for use. In addition, a family of compositions and microstructures are disclosed which achieve the necessary dissolution of each tape constituent in aqueous media.
The structure is a self-wound, water dissolvable, adhesive tape. The article comprises a plurality of microstructures of pressure sensitive adhesives that include a continuous, water dissolvable first phase material and a discontinuous, water dissolvable second phase material. The plurality of compositions of pressure sensitive adhesives for making the article include at least one organic compound incorporating one or more highly polarity functional groups. The polar functional groups include an acid functionality, an alcohol functionality, a ketone functionality, an aldehyde functionality or an ester linkage. In another embodiment, the plurality of compositions are release coatings for making the article. The release coatings include an organic compound incorporating one or more high polarity functional groups.